He gave up and got another phone. Even that needed the Android System WebView updated separately (i.e. it had not been updated along with the default automatic updates).
I’d bet it was something to do with that webview app as to why it failed on his old phone but i cant keep asking him to try things. We spent a few hours searching/chatGPT trying to figure it.
He just went out and got another phone.
Thx though.
EDIT:
If it had been possible, it would have been nice to get some kind of error message in the screen instead of just a grayed out button.